This application claims the priority of Korean Patent Application No. 2005-19705, filed on Mar. 9, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a mobile communication terminal and, more particularly, to a hybrid mobile communication terminal that supports packet data service of high data rate of up to 2.547 Mbps in a Code Division Multiple Access (CDMA) cell site in addition to supporting IS-95A/B/C voice and data services.
2. Description of Related Art
CDMA2000 is a 3rd Generation (3G) mobile telecommunications standard that uses CDMA, a multiple access scheme for digital radio, to send voice, data, and signaling data (such as a dialed telephone number) between mobile communication terminals and cell sites. CDMA2000 1x (hereinafter also referred to as “1x_Only”) is the core 3G CDMA2000 technology, and supports up to 144 kbps packet data speeds. Meanwhile, CDMA2000 1xEV (Evolution) is CDMA2000 1x with High Data Rate (HDR) capability added. CDMA2000 1x EVDO (Evolution Data Only) (hereinafter referred to as “EVDO”), a phase of CDMA2000 1xEV, supports downlink (Forward Link) data rates up to 3.1 Mbps and uplink (Reverse Link) rates up to 1.8 Mbps in a radio channel dedicated to carrying high speed packet data.
IS-856 for EVDO is a protocol different from Interim Standard 2000 (IS-2000) protocol for 1x_Only, and requires an additional base station unit (channel card) for EVDO independently of a base station unit for 1x_Only. FIG. 1 illustrates an IS-2000 radio network supporting 1x and a 1xEV radio network supporting EVDO, which are provided separately from each other. A physical layer of EVDO (IS-856) is different from that of 1x. EVDO services can be currently offered by adding devices supporting EVDO to an existing 1x_Only system.
A hybrid mobile communication terminal is a device which can access both EVDO and 1x_Only systems for packet data services. When the hybrid mobile communication terminal (hereinafter referred to as “hybrid terminal”) is powered on, it receives an overhead message over a paging channel of a 1x system and acquires the 1x system. Subsequently, the hybrid terminal receives a pilot signal over a pilot channel of an EVDO system and acquires the EVDO system. The hybrid terminal operates in a slotted mode depicted in FIG. 2 both for the 1x and EVDO systems. That is, the hybrid terminal is in a hybrid operating mode.
If the hybrid terminal is powered on in a blanket area in which EVDO services are not provided, it first acquires a 1x system and then attempts to acquire an EVDO system. However, since the hybrid terminal cannot acquire the EVDO system in the blanket area, it stops attempting to acquire the EVDO system according to the slot period of FIG. 2. That is, the hybrid terminal is set to an HDR power save mode. As a result, the hybrid terminal operates in a 1x_Only operating mode in which it can acquire only the 1x system.
In addition, when moving to the blanket area in the hybrid operating mode, the hybrid terminal cannot acquire the EVDO system and stops attempting to acquire the EVDO system according to the slot period. In this case, the hybrid terminal is set to the HDR power save mode so that it stops attempting to acquire the EVDO system according to the slot period.
However, if a user requests data services through the hybrid terminal in the HDR power save mode, the hybrid terminal first attempts to acquire the EVDO system. In this case, if the hybrid terminal fails to acquire the EVDO system, it reattempts to acquire the 1x system. That is, when the hybrid terminal acquires a system for data services in the HDR power save mode, the hybrid terminal attempts to acquire the EVDO system and then reattempts to acquire the 1x system, causing a delay in a data call connection.